Synthesis of Magnesium Hydroxide Using Post‐Reaction Filtrate as Ammonia Carrier and Morphology Analysis

Abstract This study proposes an advanced technology using post‐reaction filtrate as an ammonia carrier to synthesize magnesium hydroxide (MH) with small particles, which can benefit subsequent hydrothermal modification. In this work, the limitation of ammonia gas and ammonia water methods is avoided. The impact of operating parameters including MgCl 2 concentration, temperature, ammonia‐to‐magnesium molar ratio, feed rate, volume of ammonia mother liquor and aging time on the magnesium yield, particle size, and morphology of MH is studied. The temperature and ammonia‐to‐magnesium molar ratio are identified as key factors affecting magnesium yield. MH with a half‐content diameter of 1.70 µm and a morphology resembling small irregular flakes is successfully synthesized at a magnesium yield of 90.06%. The predictions of idea crystal habits are also performed using Morphology and CASTEP modules with Materials Studio Software. The (0 0 1) face can be preserved with the largest facet area because of the slowest crystal growth rate and the smallest attachment energy, which exhibits that MH crystals tend to be flakes.